Go to the club and talk to the ponies there. You are encouraged to make an account with an avatar, but it is not required. Be aware that the RP is most active in the hours leading up to and after midnight CST, but explicit time begins at midnight too.

A common reason for being ignored is not paying attention to where different ponies are, and interacting with ponies in different areas simultaneously, disregarding their current situation. Try reading up on Locations, watching out for ponies referencing where they are, and reacting accordingly. Otherwise it might be an issue with your character, in which case try brushing up on the rules or asking how you could improve them.

Congratulations! For reading the FAQ rather than asking, you get to avoid Pinkamena's trolling.
If the first four characters you type are "/me " (that's slash-m-e-space) then that line will be gray. (Pinkamena: Don't listen to them it's totally "/i")

There are two Pinkies who make regular appearances. First there is Pinkamena, the "normal" Pinkie. The other is PinkiusPiecus, joining us from a more Roman version of Equestria. She goes by Pinkius. Both players started playing Pinkie around the same time, and they came to this as an agreement of sorts.

Page 83 was a joke made by Spitfire referencing Choose Your Own Adventure books in regards to inevitable shipping. She said, "MyLittleRP RP is like a CYA. If you decide to go get a sammich, turn to Page 83. Page 83: AND THEN THEY FUCKED." It came into use as an abbreviation to avoid writing clopfics. It is said that every course of action eventually leads to page 83.
There have since been other pages created as well.

Once upon a time, someone RP'd Derpy. He dropped his keyboard, posting a line of text that said nothing but nb. In his honor, nb has been synonymous with derp ever since. It is used to reference synchtube's frequent "derps" that cause everyone to disconnect.